The invention relates to an apparatus for internal measurement of the exposure in photographic cameras where the light penetrating the picture-taking or objective lens is fed by way of a mirror to a photoelectric cell.
In known cameras of this kind the photoelectric cell is illuminated by way of a hinged mirror which however on release of the camera is pivoted so that the photoelectric cell receives no more measurement light. For the requirements of exposure time formation according to brightness during the photographic exposure therefore expensive electric circuit arrangements are provided which store the exposure value measured before release of the camera, for the duration of the photographic exposure. Furthermore it is known to use the marginal zone of the picture window for the arrangement of a light-sensitive cell. However this arrangement requires excessively large marginal zones, whereby the size of the picture window is impaired. Furthermore undesired and uncontrollable reflection phenomena occur on the photoelectric cell.
The object of the invention is to avoid the above mentioned disadvantages by an improved arrangement for the illumination of the photoelectric cell.